1. Field of the Invention
The present invention generally relates to a PCI interface and a PCI device, and more particularly, to a PCI extended function interface and a PCI device that uses such a PCI interface.
2. Description of the Prior Art
The configuration space in an integrated circuit (IC) is used to provide the IC on the state-of-the-art PCI (Protocol Control Information) device with the supported functions and the related information. However, the information, especially related to the supported functions, included in the configuration space is usually unchangeable. Therefore, when a plurality of IC's that support different functions are desired to be installed in a PCI device, a PCI bridge is required to be established between two IC's. It follows that a signal is firstly transmitted to a first IC in the PCI device when the PCI host (or arbitrator) requires a certain function. If the required function is not provided by the IC, the signal is transmitted through the PCI bridge on the PCI device to the next IC.
Even though such a design allows a PCI device to provide various functions, however, there still exist some problems. To begin with, since the content of the configuration space is usually unchangeable, a PCI bridge is required to serve as a medium between two IC's. Secondly, the cost for circuit design as well as fabrication will increase, since lots of PCI bridges may be required in a multi-functional PCI device.
In view of this, the present invention provides a PCI extended function interface and a PCI device that uses such a PCI interface. By employing the PCI extended function interface for the PCI device of the present invention, the content of the configuration space is thus changeable. The PCI device using such an extended function interface allows a reduced complexity in the PCI design by changing the content of the configuration space, which can do without the PCI bridges between IC's and further reduce the cost for circuit design as well as fabrication.